How to make the point from bspline include the control point?

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For example, I have 7 control point, then I use the bspline to generate the smooth line. However, I find the generated smooth points may not include the control point. The code is:

    spParametricSpline = vtk.vtkParametricSpline()
    xspline = vtk.vtkKochanekSpline()
    yspline = vtk.vtkKochanekSpline()
    zspline = vtk.vtkKochanekSpline()
    spParametricSpline.SetXSpline(xspline)
    spParametricSpline.SetYSpline(yspline)
    spParametricSpline.SetZSpline(zspline)
    # spParametricSpline.ParameterizeByLengthOn()
    spParametricFunctionSource = vtk.vtkParametricFunctionSource()
    spParametricFunctionSource.SetParametricFunction(spParametricSpline)
    spParametricFunctionSource.SetScalarModeToNone()
    spParametricFunctionSource.GenerateTextureCoordinatesOff()
    spParametricFunctionSource.SetUResolution(500)

    spSplineFilter = vtk.vtkSplineFilter()
    spSplineFilter.SetSubdivideToLength()
    spSplineFilter.SetInputConnection(spParametricFunctionSource.GetOutputPort())

    spParametricSpline.SetNumberOfPoints(X.size)
    for i in range(X.size):
        spParametricSpline.SetPoint(i, X[i], Y[i], Z[i])
    spParametricSpline.ClosedOff()
    spSplineFilter.SetLength(spacing)
    spSplineFilter.Update()
    points = spSplineFilter.GetOutput()

Is there any method to make the bspline results include the control point?